Related Rule
Practice Relating to Rule 106. Conditions for Prisoner-of-War Status
Section A. Distinction from the civilian population
The Military Manual (1993) of the Netherlands states:
[Combatants] have to distinguish themselves from the civilian population. This is a consequence of the principle that the parties to the conflict have to distinguish at all times between civilians and combatants. Combatants distinguish themselves in the first place by wearing a uniform. In addition, they have to carry their arms openly. 
Netherlands, Toepassing Humanitair Oorlogsrecht, Voorschift No. 27-412/1, Koninklijke Landmacht, Ministerie van Defensie, 1993, p. III-4; see also Handboek Militair, Ministerie van Defensie, 1995, p. 7-39.
The Military Manual (2005) of the Netherlands states:
Combatants have the right to play a direct part in hostilities. They should distinguish themselves from the civilian population. This stems from the principle that the belligerents must at all times distinguish between civilians and combatants. The latter are distinguished by wearing a uniform. Combatants must also carry their weapons openly. 
Netherlands, Humanitair Oorlogsrecht: Handleiding, Voorschift No. 27-412, Koninklijke Landmacht, Militair Juridische Dienst, 2005, § 0306.
At the CDDH, the Netherlands stated that it was convinced that “the fundamental rule of distinction between combatants and the civilian population had not been weakened by Article 42 [now Article 44]”. It stressed, however, that “the article should not be construed as entitling combatants to waive that distinction”. 
Netherlands, Statement at the CDDH, Official Records, Vol. VI, CDDH/SR.41, 26 May 1977, p. 142, § 5.